Program a Key

How To Program A Key Without A Master Key: Cheap Step-By-Step Process

Ever wonder how your car starts? How does the vehicle reach the point of ignition? Well, it is the anti-theft key that is responsible for ignition. But what happens if you lose the master key and don’t have a copy of it? 

Well, we are here to tell you how to program a key without a master key. Before we dive deeper into how you can do that, you should know what an anti-theft key is. To put it simply, an anti-theft key is an electronic device read by a computer. 

The code embedded in the device has to match the code in the software of your car. If this code does not match, your car will not start. If you happen to lose this key, there is no need to panic. 

Today, we will walk you through how you can program a key without a master key available. 

The Problem with Anti-Theft Keys

The first thing to know about how to program a key without a master key is the issue that comes with it. Generally, when people lose the anti-theft keys to their cars, they’re helpless. Because come on, who would keep a copy of the master key? Right? 

Well, don’t worry. Generally, such systems come with an RFID chipset in the key, which you can program if you lose the master key. However, this reprogramming is done by a dealer, costing you a lot of money. 

Prevention, my friend, is better than cure. So, the best preventative option for you is to make a backup master key. Nevertheless, we understand that you probably haven’t done that if you’re reading this article. So, let’s take a look at what you can do now.  

The RFID Chip

If your vehicle was manufactured during the ’90s, it came with the EEPROM as against the ECU transponder system, which is available in the newer car models. The transponder, however, is relatively easier to replace than EEPROM. 

However, let’s take a look at what the RFID chip in your car does. The RFID chip inside the ignition rings is responsible for reading the key’s signal as soon as you insert it. 

Once you have done this, the system amplifier decrypts and transmits the signal to the ECU. The ECU contains an EEPROM chip that is programmable and stores the values of the key. So, it compares the signal to the programmed code and then allows the ignition to take place.  

Now, let’s see how you can program this chip without a master key. 

Programming the Key without a Master Key: the Process

The EEPROM is located under the dashboard of your car. That is, precisely, where you will start your ‘how to program a key without a master key’ process. Here is a list of things you will need:

  • 8 pin chip programmers
  • A computer with a serial port
  • Solder gun
  • PonyProg, a free serial device programmer
  • Solder
  • 10mm socket wrench
  • Small screwdriver
  • 3 x 5V Zener diodes
  • 3 x 4.7k ohm resistors

Step 1 – Remove the EEPROM

  1. Disconnect the negative lead available on that battery of your car
  2. Now untwist the 10 mm nuts which hold the ECU in the glove compartment
  3. You will find the IC900 when you open the ECU. IC900 is a surface-mounted 93C56 EEPROM with 8 pins

Step 2 – Connect the EEPROM to your PC

  1. To connect the chip to your programmer, you can either use a chip clip or solder wires to each leg. 
  2. Once the chip gets connected to the reader, you have to connect the reader to your PC

Step 3 – Programme/Reset

  1. Launch the PonyProg software on your PC
  2. Got to ‘options’ and then ‘setup’ in PonyProg
  3. Select ‘SI Prog I/O, COM 1’ to check the communication between the software and the chip
  4. Click ‘Probe’
  5. Choose the device as ’93C56 MicroWire EEPROM.’
  6. Then click on ‘Read Device’
  7. EEPROM’s contains data in hex code format
  8. In the original dump, the virgin keys have a value of 10. Change them to ’00.’
  9. The software will now go into the auto-programming mode
  10. Leave the valet lockout untouched
  11. Click the write to EEPROM device key
  12. Disconnect everything after you get the successful write popup

Step 4 – Return the ECU to your car

Replace the ECU to your vehicle.

Step 5 – Programme the new key.

  1. Reconnect the battery of your car
  2. Insert and then immediately remove the key from the ignition lock cylinder
  3. Now your security light will remain illuminated
  4. Insert only the first transponder key into the ignition lock for a short period of 3-5 seconds
  5. Don’t turn the key 
  6. Wait for the security light to start blinking
  7. Now remove the key
  8. Carry forward the same procedure with the second transponder key
  9. The security light shall remain on, indicating that you’re still in the programming mode
  10. Repeat the same process with the third transponder key
  11. However, this time the security light will go off and then blink frequently
  12. Now, wait for another 30 seconds for the programming mode cycle to end


To summarize, you have just created two new master keys and a valet key. The third key is the valet key. Now, when you insert either of the master keys into the keyhole of your car, the security light will blink. 

However, when you insert the valet key, the security light will extinguish after staying on for two seconds. In the case of a master key, if the security light does not stop blinking, it means that your operation has failed. 

Final Thoughts

As complicated as this process sounds, it is pretty easy to perform if you are well-versed with computer terminology. While this process requires a lot of patience, it works only on cars manufactured in the ’90s. 

Models after the year 2000 come with their transponder key, which is comparatively easy to reprogram. Now that you know how to program a key without a master key, get going!



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